Depression is a serious mental health problem in the United States that has increased in prevalence over the years. Depression is estimated to affect over 17 million Americans each year. The socioeconomic impact of depression is significant; the cost is estimated to be over $44 billion annually. Further, people suffering from depression carry the risk of suicide. Up to 15% of those who are suffering from depression die by suicide. There are 30,000 to 35,000 suicide-related deaths attributed to depression a year, which is a rate similar to the death rate from leukemia.
Currently, depression is diagnosed by verbal tests that must be administered by a mental health professional. The tests rely on self-reports from the subject whereby the subjects verbally describe their feelings or are presented with verbally-described scenarios and select the scenario that best describes their feelings. The clinician then uses these responses to rate the symptoms. The rating scales provide check-lists for clinicians and diagnosticians to monitor patients' responses to treatment or reactions to environmental changes. Measuring treatment efficacy is reliant upon self-reports and verbal tests and evaluations. These tests and evaluations are limited by the reliance on verbal communication from the patient, by the requirement for administration by mental health professionals and by their subjective nature. Further, the tests do not provide a means to predict predisposition to depression.
Primary care providers may not recognize the symptoms of depression. As a result, depression may go un-diagnosed. A need exists for an objective, biochemical evaluation (e.g. lab test) that can be administered by primary care providers.
A wealth of evidence exists that depression results from an imbalance in brain chemistry. This idea has lead to anti-depressive medications based upon the inhibition of the uptake of the neurotransmitters serotonin and epinephrine.